I’ve got a sparkfun 3.3v pro-micro and when the board is powered from the usb it works fine. I get 5v on the raw pin and 3.3v on the vcc pin. Great. Lights are a normal brightness.
My issue is trying to power the board from a battery using the raw pin. I’ve tried 3 different sources, 3*AAA batteries (4.9V), breadboard power supply (5v) and an old 9v batter (7V). Each time I try these the status LED only comes on at half brightness and the serial LEDs don’t light up at all apart from one very dim flash.
Strangely when I try and power my 5V 16MHz pro-micro using the same power supply 3*AAA batteries, it works fine.
Why does the 3.3v version not liked being powered? I have two of them, brand new and both behave the same.
The 9 volt battery giving 7 volt... Is it possibly a PP3 fire alarm battery? If it is, send it to recirculation.
Check the specifications for the board to know what voltages are needed for powering it.
I think I’ve sussed it. I tried another board of the same spec I had lying around, uploaded fine, I tried powering it through AAA batteries and it lit up just right. Then after I was uploading another sketch to it I got a warning on my Mac saying ‘current draw too high device disconnected’.
After that I couldn’t power it from external power anymore, clearly a dodgy device. Have purchased another hopefully from a more reliable source!
Ahh.
You can't have the board connected to USB and RAW at the same time if the raw voltage is less than USB, and 3AAA is quite less than USB 5V.
What happend was the the USB 5V was connected through the diode to the 3.5V - 4.5V battery and that was essentially a short circuit for the USB
Everything is possible, but you wrote your board is from Sparkfun.
I wouldn't expect to have completely f...ed up boards from them.
Control your wirings, and if you feel so, send a photo here...
